Effect of gallium-substituted cobalt ferrites on the magnetic and crystallographic properties, heating ability and hemolytic cytotoxicity of nanoparticles synthesized by sol-gel for biomedical applications

The feasibility of synthesizing mixed Co1-xGaxFe2O4 (x = 0–1.0) ferrites by the sol-gel polycondensation reaction, has been demonstrated. In all cases, a single-phase spinel structure, with an average crystallite size of 14–18 nm, was detected. A decrease in final magnetization (Mf: 62.03–36.18 emu/g), remnant magnetization (Mr: 30.09–2.97 emu/g), coercive field (Hc: 1420–40 Oe), magnetic moment (n: 2.61–1.59 μB) and anisotropy constant (k: 91.75–1.51 erg/mg), are observed as gallium substitutes cobalt ions. Ferrites with x = 0.8 and 0.9 show a behavior near to that of the superparamagnetic regime. The TEM-EDS analysis shows agglomerated round nanoparticles of O, Fe, Co, and Ga with an average size of 17.75 ± 3.4 nm. The heating ability of aqueous or glycerol suspensions (10 mg of ferrite/mL of water or glycerol) was evaluated by magnetic induction testing and the application of a non-harmful field frequency for the human body (354 kHz, 9.2 kA/m). In most cases, a small increase in temperature was observed as gallium content was increased. The suspensions of the ferrite nanoparticles with x = 0.8 and 0.9 reach a liquid medium temperature above 42 °C in less than 300 s, and their SLP (Specific Loss Power) values are within a range of 1.9–23.9 W/g. The aqueous suspensions of the ferrites with x = 0.8 and 0.9 show hemolysis values of 0.37 and 0.25 %, respectively, indicating no damage to red blood cells. The results suggest that the sol-gel polycondensation reaction is an effective route to obtain pure gallium-cobalt ferrites with a behavior close to that of the superparamagnetic regime, adequate heating ability, and low hemolytic cytotoxicity, making them appropriate biomaterials for their potential use as theragnostic nanoparticles for cancer treatment and delivery systems.